Two-tone gravure printing method



Jan. 16, 1940. F. GEORGE 2,187,420

TWO-TONE GRAVURE PRINTING METHOD Filed Dec. 2 8, 1937 INVENTOR $50 6 60622? 4 ATT RNEY Patented-Jan, 16, 1940 Nl'l ED STATES PATENT oFI-ucs Fred George, Lakewood, Ohio, assignor to Interchcmical Corporation, New York, N. -Y., a corporation of Ohio Application December 28, 1937, Serial No. 182,126

1 Claim.

this invention comprises a-method of two-tone eravure printing, wherein a resilient doctor blade is so arranged with relation to a gravure plate as to leave a thin uniform film of ink over the entire surface of the plate, so that on printing, the entire surface is tinted at the same time that the etched portions of the plate deposit a deep colored design.

in gravure printing, ink is deposited from del pressions formed in a plate, generally by tooling or etching. The design is applied by flooding the plate with the ink, then removing the ink from the surface of the plate but notfrom the depressions, with an instrument commonly called a doctor blade; andthen transferring the ink from the depressions in the plate to the subject. in conventional practice, the doctor blade is a thin strip of metal which makes perfect contact with the flat top of the engraved plate, being supported thereby.

inmy copending application, Serial Number llthlllt, filed January 511937, I have disclosed a new type of doctor blade formed with a resilient surface, which gives superior results in gravure printing. I have now discovered that two-tone gravure printing can be successfully carried out by the use of such a doctor blade. A typical installation is disclosed in the drawing, in which Figure l is a side elevational view, largely diagrammatic, of a gravure printing press showing only essential elements thereof, and embodying the present invention.

Figure 2 is a detail view showing a modification ofthe doctor blade.

Figure 3 is a sectional view of the two-tone adjustment of thHoctor blade, on a greatly magnified scale.

Referring to Figure 1, I is the frame of a mature printing press, of which I I is the printing cylinder having an intaglio printing surface of the usual photogravure character. The cylinder l l is carried by shaft l2 which may be driven by suitable power means 9. I3 is a rubber-covered cylinder adapted to press the web being printed against the printing cylinder, and i4 is a metallic back-up roller for maintaining constant pressure between the rubber roller l3 and the printing cylinder throughout their length. The shafts of rollers 13 and I4 are carried in bearing blocks slidably movable in a radial direction with respect to cylinder 1 I, suitable means such as screws It: being provided for adjusting the pressure exerted by roller M. The web W of paper extends half way around roller l4, passes between that roller and roller I3, extends half way around roller l3 and passes between that roller and the printing cylinder it, after which it passes through any known and suitable mechanism for drying the printed image and rewinding the web. The cylinder it, upon which the 5 printing design is formed or mounted, is partially immersed in the ink i6 carried in an ink pan ll.

Excess ink over that required for my two-tone printing is removed by means of a doctor blade which is shown in Figure l as consisting of three 10 parts, a thin soft strip it of resilient material such as soft rubber, the end of the strip being cut square, a thicker strip it also resilient and somewhat soft or yielding, although less resilient and less soft than strip it, and a hard backing 145 strip 20, which is preferably metallic. All three of these strips are clamped firmly together by means of bars 2i and 2t and bolts it, the bars running the full length of the doctor blade. To the bar 22 are fastened brackets it, one at each end, which are secured to a shaft 25 that is journaled in the side frames of the press. To each end of shaft 25 outside of the frames of the press, there is attached an arm it, and upon these arms weights 27 of selected size may be 25 hung in order to exert forces of different amounts producing varying pressures of the doctor blade against the surface of the printing cylinder it.

As illustrated in the drawing, my doctor blade is mounted nearly but not quite tangent to the 30 cylinder, which mounting is in sharp contradistinction to the mounting of the conventional hard blade which is positioned nearly at right angles to the tangent. In practice, I have found that for average conditions the most desirable angle of the blade with reference to the tangent at the line of contact is 13 or thereabouts. This 1 angle may be varied advantageously to some extent to suit different conditions, such as changes in the speed of rotation of the printing cylinder, changes in the ink used, and changes in the pressure of the blade against the cylinder.

I have found that soft rubber, either natural or synthetic, is a suitable material for the strip l8, but it will be understood that other flexible soft materials, having more or less similar characteristics of softness and resiliency, may be substituted with good results. The two strips I8 and IQ of Figure 2 may be joined together by cement or otherwise, or they may be joined together by vulcanization.

a Flexible doctor blades using one thickness only of rubber or thelike maybe used if desired. Such an arrangement is shown in Figure 2, in which the soft flexible portion 2a of the blade is backed up by a more or less stiii metallic strip 29 and mounted in the way previously described. A single strip of rubber may also be composed of layers or zones of diflerent resiliency and softness, graded progressively from the backing to the engaging surface.

The two-tone effect is produced by adjusting the pressure between the doctor blade and the cylinder so that there is merely a touch contact between the edge of the blade and the plate. Such a contact is just sumcient to support the doctor blade in operative position. A metal blade, in such a position, would wipe the surface clean; but the resilient nature of the composition forming my blade permits the formation of a thin film of ink on the surface of the plate, as illustrated in Figure 3. Impressions made therefrom are tinted throughout, while the true deep 20 color is obtained from the design depressed in the cylinder; the result is a pleasing two-tone print.

The depth of tone in the background can be varied somewhat by varying the pressure on the blade from that necessary for line contact willcient to support the blade, to that which just removes the ink from the surface of the plate.

Changes in design and structure can obviousl be made in the machines described, without departing from the invention, which is described in the claim.

What I claim is:

The method of making a two-tone gravure print which comprises applying a continuous film of ink to a gravure plate, wiping a portion of the ink from the plate under such conditions that the wells of the plate are full and a thin uniform film of ink is spread over the surface of the plate, and printing from the plate.

FRED GEORGE. 

